1. Field of the Invention
The invention relates to a thermal development apparatus and a thermal development method for heating and developing thermal development photosensitive material, and thermal development photosensitive material used in the thermal development apparatus.
2. Description of Related Art
The thermal development apparatus comprises: for example, a temperature-controlled heating unit such as a heating drum or the like; a thermal development unit comprising a biasing component such as a roller or the like placed as opposed to the heating unit; and a cooling conveyance unit for cooling down thermal development photosensitive material heated by the heating unit. The thermal development apparatus is an apparatus that performs a thermal development process by heating and conveying the thermal development photosensitive material, while the biasing component biases the thermal development photosensitive material which is exposure-processed against a surface of the heating unit and makes the material contact the surface.
In the thermal development apparatus, in order to evenly and uniformly heat the thermal development photosensitive material, a resilient member with thermostability such as silicon rubber or the like, is placed on the surface of the heating unit for obtaining more evenness and uniformity of the thermal development photosensitive material between the heating unit and the biasing component.
For example, as disclosed in Tokuhyo-Hei 10-500497 (U.S. Pat. No. 6,007,971), in a thermal development process for heating and developing the thermal development photosensitive film (hereinafter, it is also called “film”), as a method for heating the film, the heating drum having a surface coated with the resilient member (silicon rubber) with a characteristic of thermostability and high conductivity is in practical use.
However, because of a gaseous component such as organic acid or the like emitted from the thermal development photosensitive material when the thermal development photosensitive material is heated, deterioration of the silicon rubber is accelerated. If the silicon rubber is deteriorated and altered, desired density cannot be obtained because it is impossible to heat the thermal development photosensitive material appropriately. Further, as well as the deterioration of the silicon rubber due to the above-described gas effect, the silicon rubber continuously expands and contracts and gradually grows up its shape (fattening its diameter) because of heating and cooling, and finally defection such as a crack appears on its surface. As a result, the defection causes heating unevenness, which appears on the thermal development photosensitive material as development density unevenness and non-uniformity.
Further, when the gaseous component emitted from the thermal development material, is condensed and adheres to the resilient member which has high adhesiveness such as silicon rubber or the like, it is difficult to clear away the condensed and adhering gaseous component stain despite cleaning. Furthermore, the stained part causes heating unevenness which appears on the thermal development photosensitive material as development density unevenness.
Furthermore, a diameter of the heating unit gradually differs depending on whether or not it is a path of the film due to the gas effect. If only one type of film width is processed, it will not be troublesome, but if more than two types of film width are processed, there will be unevenness caused from the smaller width film within an image range of the largest width film. Therefore, it is not possible to evenly and uniformly keep the film contacted with the surface of the heating member. As a result, it is not possible to obtain density evenness and uniformity.
As mentioned above, although there are a plurality of characteristics required of the resilient member (silicon rubber) to prevent thermal development failure at the thermal development apparatus, the resilient member in an earlier art cannot satisfy all the characteristics at once.